BMW 550i License Plate Bulb Size

The BMW 550i license plate light requires a bulb size of DE3423 for the rear exterior lighting assembly. Data for the specified component covers the span from 2006 to 2010.

The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.

Bulb Size by Year Range

Years	Bulb Type	Shop
2006-2010	DE3423	Check Price

Bulb Specifications

Description	Type	Shop
ANSI standard (US & Canada). Festoon bulb, 41mm length, end-cap contacts. 12V.	DE3423	Check Price

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Additional Notes

The BMW 550i uses the DE3423 bulb for its license plate lighting across the 2006-2010 model years.
The DE3423 is a festoon-type bulb, meaning it is cylindrical in shape and makes electrical contact through metal caps at each end rather than through a base socket or pins.
The DE3423 has a length of 41mm, which is the critical fitment factor for festoon bulbs, as the end caps must bridge the contact points within the housing correctly.
The bulb operates at 12 volts, consistent with standard automotive electrical systems.
The DE3423 designation follows ANSI standards recognized in both the United States and Canada, indicating a standardized specification rather than a proprietary part number.
Because festoon bulbs rely on physical length to maintain contact, substituting a bulb of a different length risks poor contact or failure to seat properly in the housing.